Pre-set adjustable torque measuring device



Oct. 18, 1966 K. R. LARSON FEE-SET ADJUSTABLE TORQUE MEASURING DEVICE Filed July 9, 1964 N R Rm 7 P mm a W R. v 05 w w mm ON 9 N N M w a a Wyn 9 r r H mm H //MN F MN mm Om mwmvI mm Q m; 9 xi w y Q r7/ /////M IE a w IIMN Om @N @N ATTORNEY United States Patent 3,279,287 PRE-SET ADJUSTABLE TURQUE MEASURING DEVICE Kenneth R. Larson, Des Plaines, lllh, assignor to Snap-On Tools Corporation, Kenosha, Wis, a corporation of Delaware Filed July 9, 1%4, Ser. No. 381,409 10 Claims. (Cl. 8152.4)

This invention relates to torque wrenches and more particularly to pre-set torque wrenches which are rendered inoperative when the applied turning load exceeds the pre-set torque load, although the teachings of the present invention may be employed with equal advantage for other purposes.

It contemplates more especially an improved and simplified construction of the general type described and claimed in my Letters Patent No. 2,852,972, dated September 23, 1958 wherein the turning connection is mechanically and automatically released to preclude continued load application beyond the pre-set limit.

With the teachings of the present invention, the torque resisting flexure is adjustably set between a work engaging and handle members so that fasteners such as threaded nuts and the like will be applied to prescribed torque load limits without any control exercised by the attendant during the turning operation therewith. This is accomplished through simple and inexpensive mechanical expedients that allow declutching without the hazards of uncontrollable slip that would preclude the attainment of uniform results which are essential in devices of the character involved herein.

One object of the present invention is to simplify the construction and substantially reduce the cost of mass production of torque wrenches of the type involved herein.

Another object is to provide a simple clutching and declutchirig expedient for torque wrenches of the load releasable type based upon pre-set limits of applied turning load.

Stillanother object is to provide a simple and inexpensive yieldable expedient in conjunction with clutching connectors in torque wrenches to adjustably limit the applied load without the intervention of the attendant.

A further object is to provide torque wrench clutching and de-clutching connectors between the load applying member and the work engaging member, of improved and simplified construction and operation.

A still further object is to provide roller clutch elements in conjunction with a simple yieldable support therefore whose density can be varied to render the limit load control adjustable.

Still a further object is to provide an improved roller clutching and de-clutching device for torque wrenches that is simple, inexpensive and dependable in construction and operation.

Other objects and advantages will appear from the following description of an illustrated embodiment of the invention.

In the drawing:

FIGURE 1 is a fragmentary enlarged front view of a torque Wrench embodying features of the present invention.

FIGURE 2 is a side sectional view of the fragmentary wrench shown in FIGURE 1 taken longitudinally through the handle member with the head portion intact and not in section.

FIGURE 3 is a side sectional view in elevation similar to FIGURE 2 with all the parts including the head portion in section to clarify the showing.

FIGURE 4 is a view in section similar to FIGURE 3 with the yieldable clutching device element densified to adjust the pre-setting thereof sothat the limit load of de-clutching may be varied for different tightening operations.

FIGURE 5 is a sectional view taken substantially along line V-V of FIGURE 3.

FIGURE 6 is a fragmentary sectional view taken substantially along line VI-VI of FIGURE 3.

The structure selected for illustration is not intended to serve as a limitation upon the scope or teachings of the invention, but is merely illustrative thereof. There may be considerable variations and adaptations of all or part of the teachings depending upon the dictates of commercial practice. The present invention comprises an elongated flat composite handle member 10 which, in this instance, is fabricated from fiat plates 11-12 to confine a plate 13 therebetween for rotary movement therewith. The handle plates 11-12 are provided with aligned bores 1445 to receive a work engaging member 16 which is journalled therein and is connectible and disconnectible with the handle member 10 as will appear more fully hereinafter to control the limit of tightening operations on fasteners and the like.

The intermediate plate 13 is, in this instance, provided with an enlarged interiorly serrated bore 17 of the ratchet type, but which could be of any geometrical configuration to register and turn with the complementally shaped collar 18 carried by the work engaging member 16 between it and a cupped cylindrical member 19. The cupped member 19 conforms in exterior diameter with the shoulder 20 of the Work engaging member 16 which is provided with a polygonal stub 21 provided with a standard spring impelled ball detent to retain variously sized wrench sockets thereon for turning nuts and other fasteners to a predetermined degree of tightness measured by the moment arm or torque load applied to the handle member 101112.

The cupped member 19 telescopically fits over a cylindrical shank 23 formed integral with the work engaging member 16, and is held thereon by a set screw 24 provided transversely through the wall thereof having a threaded aperture 25 for the threaded reception thereof. A comparatively larger threaded screw plunger 26 that aligns with a correspondingly threaded aperture or bore 27 provided axially in the cylindrical work engaging head shank 23 to retain a resilient or flexible member at a predetermined degree of compression as will be presently described. The set screw 24 engages, in turn, the surface of a larger set screw plunger 26 which threadedly engages an axial bore 27 of the cylindrical shank 23 comprising part of the work engaging member 16. The set screw plunger 26, in this instance, axially engages a yieldable or resilient plug 28 which is shaped to loosely fit into the axial bore 27 of the work engaging member tubular shank 23 for confinement by the set screw plunger 26 which pre-sets the density of the resilient plug 28 made from suitable rubber or any other suitable material which has no recognizable variation in elasticity over an extended period of time and irrespective of the number of vacillations in elasticity which is imparted thereto in its service as a fiexure resisting expedient as will appear more fully hereinafter.

The elastic or yieldable plug 28 may consist of die rubber which is compressible to a limited degree and still will recoil or return to its original precise and preloaded shape and density for an almost infinite number of flexings and perhaps more unlimited in number than many other yieldable and elastic substances. An end axial aperture 29 is provided in the cupped member 19 to enable access to the slot 30 in the end of the set screw plunger 26 with a screw driver or other tool for adjustment of the set screw plunger 26 in relation to the die 3 rubber torque responsive member 28, in this instance the cylindrically shaped die rubber plug 28 to pre-load same or adjust the pre-loading thereof to yield a Limited degree responsive to external pressure thereon as will appear presently from a description of its function and operation for this particular application.

To this end, a plurality of rollers 31, in this instance four, are freely displaceable in radial slots 33 equidistantly spaced in the cylindrical shank 23 adjacent the work engaging member 16. The rollers 31 are, therefore, circumferentially and equidistantly positioned around and in contact with the yieldable plug 28 (FIGURE 6) to ride in a serrated circular track 32 provided axially within the collar 18 whose serrated or polygonal exterior 17 is in engagement with the complemental bore 17 of the plate member 13. With this arrangement, the rotary action of the handle member 10 consisting of plates 11- 1213 will cause the rollers 31 to contact the cylindrical surfaces of the yieldable plug 28 so long as they are lodged within and in registry with their confronting complemental valleys or notches 32 in the serrated collar 18. This occurs when the plug 18 is pre-loaded to support the rollers in their valleys or notches 32. As soon as the torque load applied manually to the handle 10 exceeds the pre-loading of the plug 28 and the latter begins to yield by the reaction of the rollers 31 riding out of their valleys or notches in the serrated opening 32, the roller pressure on the yieldable plug 28 will increase and the latter will yield sufliciently to allow the rollers 31 to ride over the nodes thereof and disconnect the handle 10 from the Work engaging member 16. This precludes the fastener or threaded nut to be turned any further and thus the torque load in tightening same is uniformly controlled without the intervention of the operator or with errors in human responses which could otherwise result in depending upon a visual indicator for the operator to watch and respond to.

It should be noted that as the set screw plunger 26 is manually screwed into the threaded aperture or bore 27, the yieldable plug 28 is compressed and further preloaded so that it will take greater loads for turning the work engaging member 16 before the rollers 31 are permitted to recede inwardly against the plug 28 so that the handle will be disconnected at a higher applied torque turning load which can be determined accurately on a calibrated test device designed for checking the accuracy of torque wrenches. Conversely, the unscrewing of the set screw plunger 26 will decrease the torque load presetting in that the plunger 28 is more elastic when it is subiected to a lesser compression or density. Thus the de-clutching takes place at a lower torque load as determined by the setting of the set screw plunger 26. Torque wrenches of this type are designed for production line operations where the torque load turning operation is uniform for a large number of devices before requiringre-setting.

While I have illustrated and described a preferred embodiment of this invention, it must be understood that the invention is capable of considerable variation and modification without departing from the spirit of the invention and its concepts. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

I claim:

1. In a pre-set torque measuring release Wrench, the combination with a handle member, of a work engaging member journalled for rotation in said handle member, clutching and declutching means interposed between said work engaging member and said handle member to establish a connection therebetween when the torque turning moment is within the pre-set magnitude and to eifect a release therebetween when the torque turning moment is above the pre-set magnitude, said clutching and declutching means including radially yielding and an axially disposed body member for resisting said clutching and declutching means which maintain the parts in engagement for turning of said work engaging member up to the predetermined torque load applied to the handle member.

2. A pre set troque measuring wrench defined in claim 1 wherein said yieldable means cooperates with adjusting means to vary the pre-set maximum torque load beyond which said declutching means become operative.

3. A pre-set torque measuring wrench defined in claim 1 wherein said yieldable means comprises a compressible plug for resisting the displacement of said clutching and declutching means.

4. A pre-set torque measuring wrench defined in claim 3 wherein said clutching and declutching means comprises one or more rollers and a serrated ring member in confronting relation therewith.

5. A pre-set torque wrench defined in claim 2 wherein said yieldable means comprises a compressible axial plug.

6. A pre-set torque wrench defined in claim 5 wherein opposed pairs of rollers are supported by said axial plug to maintain the connection between said handle member and said work engaging member.

7. A pre-set torque wrench defined in claim 6 wherein said rollers confront a serrated ring member defining a circular path while said rollers are supported in torque resisting engagement with said axial plug.

8. A pre-set torque measuring wrench of the releasable type defined in claim 1 wherein said clutching and declutching means embody an internally serrated ring member on said work engaging member, a compressible axial plug extending through said serrated ring member, and a plurality of rollers interposed between said serrated ring member and said axial plug. 9. A pre-set torque measuring wrench defined in claim 8 wherein said compressible axial plug confronts adjusting means to vary the density thereof for changing the preset torque load at which said clutching means operate as declutching means.

10. A pre-set torque measuring wrench defined in claim 8 wherein said compressible plug confronts a threaded axial screw member to vary the density of said compressible plug to predetermine the torque load at which said handle member and work engaging member are rendered inoperative for further turning movement as a rigid unit.

References Cited by the Examiner UNITED STATES PATENTS 2,441,038 5/1948 Siesel 6429 2,848,883 8/1958 Dallolio 64-29 2,852,972 9/1958 Larson 6429 X 3,157,258 11/1964 Cronholm 64-28 X Y FOREIGN PATENTS 1,163,613 2/1964 Germany.

WILLIAM FELDMAN, Primary Examiner. JAMES L. JONES, JR., Examiner. 

1. IN A PRE-SET TORQUE MEASURING RELEASE WRENCH, THE COMBINATION WITH A HANDLE MEMBER, OF A WORK ENGAGING MEMBER JOURNALLED FOR ROTATION IN SAID HANDLE MEMBER, CLUTCHING AND DECLUTCHING MEANS INTERPOSED BETWEEN SAID WORK ENGAGING MEMBER AND SAID HANDLE MEMBER TO ESTABLISH A CONNECTION THEREBETWEEN WHEN THE TORQUE TURNING MOMENT IS WITHIN THE PRE-SET MAGNITUDE AND TO EFFECT A RELEASE THEREBETWEEN WHEN THE TORQUE TURNING MOMENT IS ABOVE THE PRE-SET MAGNITUDE, SAID CLUTCHING AND DECLUTCHING MEANS INCLUDING RADIALLY YIELDING AND AN AXIALLY DISPOSED BODY MEMBER FOR RESISTING SAID CLUTCHING AND DECLUTCHING MEANS WHICH MAINTAIN THE PARTS IN ENGAGEMENT FOR TURNING OF SAID WORK ENGAGING MEMBER UP TO THE PREDETERMINED TORQUE LOAD APPLIED TO THE HANDLE MEMBER. 